1. Field of the Invention
The compounds of the present invention are imidazo[1,5-a]quinoxalines (I) which are useful pharmaceutical agents.
2. Description of the Related Art
Many commercially available anxiolytic agents are from the chemical group known as benzodiazepines. The benzodiazepines are characterized by a seven member ring attached to an aromatic ring.
U.S. Pat. No. 4,774,245 discloses a group of non-benzodiazepine anxiolytic which posses a six member ring rather than a seven member ring attached to the aromatic ring (imidazo[1,5-a]quinoxalines). These compounds have an endocyclic carbonyl group.
EP 344,943A discloses a group of imidazo[1,5-a]quinoxaline compounds, useful as anxiolytic and anticonvulsant agents, having an exocyclic carbonyl at the N.sub.5 position attached to a methyl group and not attached directly to the N.sub.5 nitrogen, and an endocyclic carbonyl at C.sub.4.
EP 347,094A discloses imidazo[1,5-a]quinoxaline-4,5-enes useful for treating CNS disorders with no substitution at N.sub.5.
EP 320,136 discloses N.sub.5 -isopropyl-imidazo[1,5-a]quinoxalines having an endocyclic carbonyl at C.sub.4, useful as anxiolytic and anticonvulsant agents.
EP 368,652A discloses N.sub.5 -(t-butyl)-imidazo[1,5-a]quinoxalines having an endocyclic carbonyl at C.sub.4, useful as anxiolytic and anticonvulsant agents.
EP 283,162A discloses imidazole fused ring compounds of varying types including quinoxalines. The quinoxalines have an endocyclic carbonyl group and alkyl substitution at N.sub.5 or 4,5-ene and were useful as anxiolytic and anticonvulsant agents.
BE 878,028 and 881,631 disclose imidazo[1,2-a]quinoxaline-2-carboxylic acids, and derivatives, useful for treating allergic asthma and asthmatic bronchitis.
U.S. Pat. No. 4,128,716 discloses 4-halo-4,5-ene-pyrazolo[1,5-a]quinoxaline-3-carboxylates useful as antiinflammatory agents.
U.S. Pat. Nos. 4,774,245 and 4,795,749 (EP 220 845 A) and EP 0 225 013 A discloses N.sub.5 alkyl and cycloalkyl substituted imidazo[1,5-a]quinoxalines without an endocyclic carbonyl. The imidazo[1,5-a]quinoxalines (I) of the present invention have a --CO-- or --CS-- in the side chain attached to N.sub.5.
U.S. Pat. No. 5,075,304 discloses imidazo[1,5-a]quinoxalin-4-ones with a carbonyl function at C.sub.4 and a (substituted) methyl at N.sub.5 (--CH.sub.2 --CO--O-alkyl) useful as anticonvulsants, anxiolytics and hypnotics.
International Publication WO 92/22552 is the parent PCT application of the national phase application.
The imidazo[1,5-a]quinoxalines (LX) of the present invention do not have a --CO-- or --CS-- in the side chain attached to N.sub.5.